Arthroscopic Hip Surgery: Frequency of Postoperative MR Arthrographic Findings in Asymptomatic and Symptomatic Patients

Purpose To determine and compare the frequency of imaging abnormalities in asymptomatic and symptomatic patients after arthroscopic hip surgery. Materials and Methods This study was approved by the institutional review board. Informed consent was obtained from all patients. Thirty-four patients (17 asymptomatic and 17 symptomatic patients) underwent 1.5-T magnetic resonance (MR) arthrography of the hip 1 year after arthroscopic treatment of femoroacetabular impingement. Two readers independently analyzed all MR arthrographic images for the presence of abnormal imaging findings, including capsular adhesions at the femoral neck, obliteration of the paralabral sulcus, labral defects, and defects of the hip capsule in several anatomic positions (anterior to posterior). Postoperative findings were compared with linear and generalized linear mixed-effects regression models. Results Capsular adhesions at the anterior femoral neck were present in 12 of the 34 patients (35%), and there were no differences between the groups or readers (P = .99). The paralabral sulcus was obliterated in at least one anatomic location in 94% (reader 1, 32 of 34 patients) and 100% (reader 2, 34 of 34 patients) of patients (P = .99). Residual labral tears were detected in 35% of asymptomatic patients (six of 17 patients) and 41% of symptomatic patients (seven of 17 patients) by reader 1 and in 53% of asymptomatic and symptomatic patients (nine of 17 patients in each group) by reader 2, without significant differences between the groups (P = .81). Defects of the hip capsule were more common in asymptomatic patients (77% [13 of 17 patients] for reader 1 and 53% [nine of 17 patients] for reader 2) than in symptomatic patients (59% [10 of 17 patients] for reader 1 and 47% [eight of 17 patients] for reader 2), but without significant differences (P = .33). Conclusion Obliteration of the paralabral sulcus was the most frequent finding after arthroscopic hip surgery in both asymptomatic and symptomatic patients, and capsular adhesions at the anterior femoral neck were present in 35% of patients in both groups.